The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Recently, various mobility vehicles using electricity such as scooters, bicycles or electric transportation devices have been developed. Since electric transportation devices are environmentally friendly in that they do not produce harmful emissions and can be more compact, the electric transportation devices are becoming more popular as personal transportation devices. Such personal transportation devices may be very useful and convenient on busy city streets concerning its speed, compactness, and mobility.
The personal transportation device includes a riding unit, occupied by a rider, a driving unit, and a steering unit. The riding unit may be configured as a footplate, on which the rider stands, or a seat on which the rider sits. The driving unit may include driving wheels, an electric motor for driving the driving wheels, and a battery for supplying electric power to the electric motor. The steering unit may be configured as handlebars, which the rider directly holds for steering, or a sensor for sensing a center of gravity, a tilt or the like.
In particular, as a personal transportation device, various kinds of two-wheeled personal mobility vehicles have been released on the market. The two-wheeled mobility vehicle has a turning radius equal to zero so that it may be able to move freely in a narrow space.
Such a two-wheeled mobility vehicle may further include a control mechanism to stabilize the physically unstable structure. However, in the event of breakdown or malfunction of the control mechanism, the rider may be susceptible to a risk of injury. Therefore, the two-wheeled mobility vehicle may not be appropriate for high-speed travel.
Meanwhile, a three-wheeled mobility vehicle may be more physically stable than the two-wheeled mobility vehicle, but the turning radius may be relatively large as opposed to that of the two-wheeled mobility vehicle. Further, when the three-wheeled mobility vehicle turns at that turning radius, it may roll over due to centrifugal force.